Do a google search on Torcelli's law and you will find something that will at least get you the theoretical number. Then dust off your calculus book to account for changing water elevation if you are interested in the value over time.
Justin D. Reid, P.E. RLH Fire Protection 16735 Saticoy St. #110 Van Nuys, CA 91406 213-798-0251 Sent from my iPhone On Aug 6, 2009, at 9:59 AM, David de Vries <[email protected]> wrote: > Greg: > > I looked up a couple more things. Can't find anything on vortex > plates, but a Borda entrance (where the open end of the pipe is > above the bottom of the tank, rather than flush) adds about 20 feet > to your pipe length. The open discharge, if you really had one, > would add another 3 feet. To be cautious, I would add 50 feet for > the entrance, discharge and vortex plate. This knocks down your > flow to 6950 gpm with zero residual, or about 4300 gpm at 35 psi > residual. Still comfortably above your demand. > > Contact me off-Forum if you need any of the reference material. > > Dave > > David A. de Vries, P.E., CSP > Firetech Engineering Incorporated > > > > > --- On Thu, 8/6/09, David de Vries <[email protected]> wrote: > > > From: David de Vries <[email protected]> > Subject: RE: water storage tank > To: [email protected] > Date: Thursday, August 6, 2009, 11:08 AM > > > > Greg: > > You can make some assumptions about your situation to get into the > ballpark. This is basically a civil engineering water supply > problem -- an infinitely large reservoir discharging through an open > pipe with a certain static head. > > Use Hazen Williams and solve for Q. > > Assume the 8" is Sch 30 steel, C=120, diameter 8.071, length the > water is traveling is 140 feet. If it is an open pipe, the side-on > pressure at discharge is zero (its all velocity pressure at that > point). Plug those numbers into HW and you get something like 8000 > gpm at zero residual pressure. So at 35 psi you've got a flow of > about 4800 gpm. > > Fine tune that using the actual pipe configuration as Craig pointed > out, then Bernoulli and adjust for total energy (velocity pressure, > static pressure and elevation pressure) and you can get a more > precise answer. > > Dave > > David A. de Vries, P.E., CSP > Firetech Engineering Incorporated > > > > > --- On Thu, 8/6/09, Greg McGahan <[email protected]> wrote: > > > From: Greg McGahan <[email protected]> > Subject: RE: water storage tank > To: [email protected] > Date: Thursday, August 6, 2009, 10:18 AM > > > I am getting info piecemeal from the engineering firm that is in > charge of the tower. They say they don't > Know what the residual pressure and flow will be when the tower is > completed. We have a sprinkler system going in "next door" to the > tower using the existing water from the old system. However, they > have installed a 4" pipe with a hydrant instead of 6" (many years > ago)and nobody knew until we dug it up. > > Now we are flowing 600 gpm through a 4" pipe to our source and the > calcs are too close for comfort. We are looking for a "guesstimate" > of the available water at the base of the tower without any fittings > or valves. I can add them in the 8" line from the base to the new > tie in point where the systems tie together. We are talking about > needing to pick up 5 to 10 psi not 20 or 30, so as long as we are > close we should be good. > > This really should fall on the EOR, but as is often the case in this > region, if we want to finish the job on time, we have to get an > answer immediately. > > So I can say that I should reasonably be able to expect .156 x 140' > = 22 lbs of loss from the tank to the bottom w/o > fittings....therefore if we say we should reasonably expect 1,500 > gpm at 35 psi? > > > Greg McGahan > Operations Manager > > Living Water Fire Protection > 1160 McKenzie Road > P.O. Box 877 > Cantonment, Florida 32533 > (850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 > [email protected] > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Thursday, August 06, 2009 9:28 AM > To: [email protected] > Subject: RE: water storage tank > > You're asking an open ended question. Sorry for running you around > in circles. > > There are too many unknown variables here that are needed to make > any kind of determination. > > Like has been said, how much pipe, fittings, valves, elevations, > what kind of discharge gpm, etc. etc, etc. > > Plus the value at what tank level, since the tank head will affect > the residual pressure. > > If you go by the flow required to produce a 10 fps velocity out of > NFPA 24 for instance, that flow rate for an 8" would be 1560 gpm. > > If you use cement lined DI pipe at 1560 gpm the pressure drop is . > 156 psi/10ft. > > Ina real simplistic format, if you had 20 ft of pipe, static of 70 > psi, flowing 1560 gpm, the line loss equals .313 psi. Use 1560 gpm > and 69.6 psi for the K-factor which comes out to K=197.8. > Naturally the gpm will be slightly less than at the discharge but > that difference would be negligible at these variables. > > This is all nominal since like I said the value will vary depending > on tank level and other unknowns. > > > > Craig L. Prahl, CET > Fire Protection Specialist > Mechanical Department > CH2MHILL > Lockwood Greene > 1500 International Drive > PO Box 491, Spartanburg, SC 29304-0491 > Direct - 864.599.4102 > Fax - 864.599.8439 > [email protected] > http://www.ch2m.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Greg > McGahan > Sent: Thursday, August 06, 2009 9:37 AM > To: [email protected] > Subject: RE: water storage tank > > Guys, I know all of the basic hydraulic stuff....I do NOT know the K > factor of an 8" open pipe and don't feel comfortable guessing at > formulas. I went to college and I know there is a formula that will > easily tell you a reasonable expected flow and pressure. Bu that was > a long time ago. > > Greg McGahan > Operations Manager > > Living Water Fire Protection > 1160 McKenzie Road > P.O. Box 877 > Cantonment, Florida 32533 > (850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 > [email protected] > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Thursday, August 06, 2009 8:29 AM > To: AFSA > Subject: Re: water storage tank > > That depends on flow rate Greg. Higher flow = higher loss per ft. > Longer run = higher loss at specified flow rate. > > > > > Sent from my Verizon Wireless BlackBerry > > -----Original Message----- > From: "Greg McGahan" <[email protected]> > > Date: Thu, 6 Aug 2009 08:06:45 > To: <[email protected]> > Subject: RE: water storage tank > > > I know the static pressure. I need the RESIDUAL pressure and flow > through an open 8" pipe at ground level. > > Greg McGahan > Operations Manager > > Living Water Fire Protection > 1160 McKenzie Road > P.O. Box 877 > Cantonment, Florida 32533 > (850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 > [email protected] > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Thursday, August 06, 2009 7:28 AM > To: [email protected] > Subject: RE: water storage tank > > The formula is: ft of water x .433 = psi > > So for 140 ft of head the approximate psi would be around 60 psi, at > 70 ft it would be approximately 30, etc. > > Note that this does not account for the loss through the tank > outlet, vortex plate valves or piping loss. > > Find out what that 8" is. Especially if it's a plastic. Beware of > HDPE. > > > Craig L. Prahl, CET > Fire Protection Specialist > Mechanical Department > CH2MHILL > Lockwood Greene > 1500 International Drive > PO Box 491, Spartanburg, SC 29304-0491 > Direct - 864.599.4102 > Fax - 864.599.8439 > [email protected] > http://www.ch2m.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Greg > McGahan > Sent: Thursday, August 06, 2009 8:18 AM > To: [email protected] > Subject: water storage tank > > We have a situation where a new water storage tank is being > installed on a public utility system and I need some help if anyone > can tell me the following: > > New Tank - 140' high > > 8" pipe (unknown type) going straight to ground level > > What is a reasonable expected flow and residual pressure? > > Any help would be appreciated. > > Greg McGahan > Operations Manager > > Living Water Fire Protection > 1160 McKenzie Road > P.O. Box 877 > Cantonment, Florida 32533 > (850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 > [email protected] > > > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) > _______________________________________________ > Sprinklerforum mailing list > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:Sprinklerforum- > [email protected] > (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
